Instructions
Navigate to the "My Xbox" tab from the main menu of the Xbox 360. Select "Windows Media Center."
Scroll through the pages you are shown to receive the Media Center Setup Key. Write this eight-digit code down.
Open the "Start" menu, then "Windows Media Center" on your computer. Choose "Tasks," then "Add Extender."
Type in the eight-digit Media Center Setup Key and click "OK" to complete the setup.